The present invention relates to a field adjustable pressure reducing valve that is particularly useful, for example, in a high-rise building application in a fixed fire protection system.
In high-rise buildings, the riser pipe of the fire protection system, which is typically located in a stairwell of the building, operates with a relatively high pressure in order to have a sufficient operating pressure at the highest elevation of the building. When firefighters need to access the water in these fire protection systems, for example in the riser pipe, the pressure in the system typically exceeds the maximum pressure ratings for the fire protection components. In addition, at the lower elevations, the pressure may exceed pressure ratings for the sprinkler piping components.
In order to reduce the pressure, fire protection systems have incorporated pressure reducing valves, which reduce the pressure at the valve and are located at intermediate elevations along the riser so that the water pressure is reduced at these locations to acceptable levels for firefighting equipment and for the sprinkler piping. To reduce the pressure, pressure reducing valves incorporate springs that counteract the pressure exerted on the valve piston generated, for example, in the riser pipe.
Because pressure reducing valves used in fire suppression applications deal with relatively high pressures (greater than 175 psi), the force required by these springs may often be quite large, for example, on the order of up to 2000 to 3000 lbs. To generate these large spring forces, however, the springs are relatively large in height. The larger height equates to more coils to distribute stress load. For example, in some applications, the spring may be 6 inches or taller.
However, the large height of the spring creates multiple problems. For example, with the taller springs, the size of the valve, which encloses the spring, is necessarily increased. Hence, the weight of the valve can be significant. Also, with increased size comes increased material cost. In addition, pressure reducing valves for the fire suppression industry are constructed of brass, which is cast. Hence, in addition to the material cost increase, the cost for the casting process and casting equipment will increase. The added weight and bulk of the valve also results in the valve being more difficult to handle and, therefore, also increases the shipping and handling costs. The large size of the valve also makes it impractical to use in a tight area—therefore, its use may be limited in some applications or locales. As a result, many contractors will not use field adjustable pressure reducing valves because of these size/weight issues.
Consequently, there is a need for a pressure reducing valve with a more compact configuration, without comprising the function of the pressure reducing valve.